LDH-derived catalysts for complete oxidation of volatile organic compounds

The Cu,Cr-, Zn,Cr- and Cu,Al-layered double hydroxides have been synthesize d by the coprecipitation method and characterized by elemental analysis, PX RD, SEM/EDS and BET. The mixed oxide materials obtained upon calcination at 873 K show very high catalytic activity for the combustion of toluene and ethanol. The best sample is derived from the Cu,Cr-LDH precursor with a Cu: Cr ratio of 2, composed of copper oxide and copper chromite. This catalyst gave 50% conversion of toluene and ethanol at temperatures of 15 and 15 K l ower, respectively, than the reference commercial catalyst. Catalytic tests with a mechanical mixture of CuO and CuCr2O4 demonstrate that the use of a n LDH precursor is essential for optimum results. The importance of the sim ultaneous presence of both Cu and Cr, the influence of the Cu:Cr ratio on t he catalytic activity and the role of the interface boundaries in the CuO-C uCr2O4 mixed oxide system are discussed.